With rapid progress of display technologies, touch screens have widely merged into people's life. Currently, touch screens can be classified into an Add on Mode Touch Panel (AMTP), an On Cell Touch Panel (OCTP) and an In Cell Touch Panel (ICTP) in terms of their composition. The AMTP is a liquid crystal (LC) display screen with touch function formed by manufacturing a touch screen and a LC display screen separately and then bonding them together. However, the AMTP has disadvantages such as high manufacturing cost, low light transmission, thicker modules and so on. The ICTP integrates touch electrodes of the touch screen inside the LC display screen, thereby reducing overall thickness of the modules and reducing the manufacturing cost of the touch screen dramatically. Therefore, the ICTP is welcomed by panel manufacturers.
Currently, the capacitive ICTP has various design schemes. Typically, a touch driving electrode and a touch sensing electrode are disposed inside a LC cell to form coupling capacitance between the touch driving electrode and the touch sensing electrode. When a human body touches the touch screen, the human body electric field as formed would affect the capacitance value of the mutual capacitance, and thus change the voltage signal coupled by the touch sensing electrode. The touch position can be determined according to the change of the voltage signal. In order to implement the structural design of the above capacitive ICTP, it is usually required to arrange a corresponding touch read signal line separately for each touch sensing electrode and a corresponding touch scan signal line separately for each touch driving electrode in a Thin Film Transistor (TFT) array substrate. In order to perform touch scan for touch driving electrodes, a separate touch driving chip is typically used to directly supply touch scan signals. However, it needs a large wiring area and a number of chip pins, which is not advantageous to realize narrow bezel design of the touch screen and reduce cost.